It is known that extremely large quantities of ores exist on the sea bottom and that, in particular, mineral rich nodules exist in many parts of the world. They contain essentially manganese and also other metals such as iron, nickel, molybdenum, cobalt and copper, and therefore constitute a very sought-after inexhaustible source of ores. However, these nodules are usualy found at great depths, e.g., at 5500 meters below the surface of the sea, so that extremely difficult technological problems must be solved for their exploitation.
Indeed, the picking up of the nodules on the sea bottom in deep oceans, and then the raising of these nodules over such a distance to the surface, is an operation difficult to carry out in an efficient manner since, at this depth, the pressure is high and the action of the wind and swell on the surface and the deep-sea currents must moreover be taken into account.
For the extraction of these nodules, apparatus or methods exist which employ, in combination with a ship or platform on the surface, suction systems, bucket dredgers or like means, but these various devices have not given full satisfaction both because of difficulties encountered in the precise control or guidance of the apparatus at these depths, and because of the power required for raising the nodules from the bottom up to the surface of the sea.
Apparatus is also known which employs devices capable of travelling over the sea bottom and equipped with nodule pick up and storing means. These devices may be pulled along by a cable from the surface or be self-propelled and previously programmed to operate on the sea bottom. Some thereof have their own source of energy and can be moreover designed in such manner as to effect not only the taking up of the nodules but also the raising thereof to the surface.
However, these various equipments have the drawback of not permitting sufficient efficiency in the picking up of the ore in a given period of time and for a given area passed over.